A Japanese-sponsored conference, convened by an organization known as Gensuikin — Congress Against Atomic and Hydrogen Bombs — was deadlocked today because the organizers, bowing to Arab pressure, refused to seat an Israeli delegate.

The group tried to reject the credentials of Yitzhak Patish, political secretary of the Mapam Party, after Arab delegations charged him with representing an “expansionist” state. The credentials committee ruled that it could not recognize Mr. Patish because it opposes “territorial expansion by armed forces.”

Delegates from Britain, the United States and New Zealand came to the defense of the Israeli. The conference could not adopt a decision on admitting or rejecting Patish due to the disagreements between the delegations upholding Mr. Patish and the Arab states opposing him.